This relationship is not why my marriage is failing - in fact, it's made me see things about myself and marriage in a different way.

I think my marriage has failed largely because of a natural progression (which I think many married people experience today), though I am aware my infidelity has been a factor.

The question 'Were we meant to mate for ever?' comes to my mind when I use the term 'infidelity'.

What do you think? People keep advising me to work on my marriage - but I don't feel there's anything left to work on.

I think we have drifted too far apart. I can't think of any similarities between us at all.

My philosophy in life has taught me to be concerned about our journeys and worry less about our destinations, but I'm also aware that every action has a reaction and am concerned about everyone's future here - especially my daughter's.

I do love my wife, but I'm not in love with her any more. I don't think I will ever be.

As much as I feel sorry to leave her, I feel that there is no good reason for us to continue as husband and wife.

The only reason for us to continue with this marriage is for our child. But is that enough?

I feel I am denying myself if I continue. I have never written to someone like you. Please help me, my wife and our little girl.

Jon

Many people think fidelity is not a natural state.

In the 18th century, James Boswell asked Samuel Johnson: 'Pray, Sir, do you not suppose that there are 50 women in the world, with any one of whom a man may be as happy as with one woman in particular?'

Johnson replied: 'Aye Sir, 50,000.' Cynical exaggeration aside, I have often wondered if sometimes fidelity is more a matter of opportunity than virtue.

That's not to say there aren't plenty of men and women who, having fallen in love and made their vows, never hanker after an illicit partner.

They're the lucky ones - in love for life. Yet for countless others, even happily married, the grass will sometimes seem greener, if only for a while.

Do you act on it? Well, given the chance, some people will - even if it ends in tears.

Many women will be irritated by the rather smug, self-serving tone of your letter - and one of them might be your girlfriend.

You are 'almost certain' that she and you are 'meant for each other in many ways'.

If I were her, I wouldn't count that as a ringing endorsement, even though you say you have a 'wonderful affinity'.

She is married, you have a two-year-old daughter; you know damage will be done if you leave, so what do you want me to say?

It's clear you have utterly given up on this marriage; when friends advise you to hang in and try to make it work, you say there's nothing to work on.

If you won't listen to them, what do you want from me - a stranger?

Maybe I can be useful with home truths. You've been having an affair for 'a few years', yet your daughter is just two.

So you were having sex with your wife and knowingly fathered a child even though your mind (as well as the rest of you) was engaged elsewhere.

You say your marriage has failed due to 'natural progression', but then admit (rather reluctantly) that your affair has been a cause, too. Well, of course it has!

Since you conceived your daughter, you have allowed your marriage to go downhill, and you almost certainly wouldn't have done so if you hadn't had a lover.

That's why adultery is called adultery - because it 'adulterates', which literally means to make something poorer in quality by adding another substance.

Surely you are deluding yourself in thinking the affair 'has brought a strange balance' to your married life?

From where I'm sitting, there is nothing unique about your story and I can't see the equilibrium.

You and your girlfriend are on an even footing, yet both your spouses are being deceived.

Even within yourself you are not balanced, but wobbling in a state of helpless dissatisfaction.

You tell me - with what I take as a note of pathetic helplessness - that 'we have no control over the future'.

This is nonsense! You and your girlfriend are adults with responsibilities, and you have to start making mature decisions instead of vacillating.

Since you've concluded that your marriage is over, the situation must be very unhappy indeed for your wife - even if she doesn't know the truth.

You say you have feelings for her, so treat her with respect.

I have written before that some love affairs are (sadly for those who suffer) destined to 'release' the two lovers into a long-lasting happiness; therefore, I am the last person to wag a judgmental finger.

Some marriages are better ended; some benefit from work and sacrifice.

Who can know what's right in your case? All I would say is that you sound like somebody who doesn't truly know that self he says he is 'denying'.

Concentrating on the 'journey' is all very well, but not if it leads round in circles. Your 'destination' should be a stable life with whichever of these women you truly love; deciding that, you must act with consideration to resolve the issue.

If it's your wife (and I hope so) you must give up your lover. If it's the girlfriend, you must tell your wife - and face up to her hurt.

And you must vow to be considerate, unselfish and loving in breaking up that marriage - for your wife and child are part of your life's journey and how you treat them could be your biggest test.

My Top Gear fantasy is taking over my life

Dear Bel

I am a 40-year-old, professional, intelligent, attractive and, up to this point, emotionally stable Christian woman who has developed a 'crush' for the first time.

I have fallen completely in love with the TV presenter James May, who is totally unobtainable - and I have no idea how to deal with this, or how to stop my unconscious feelings.

I cannot wait to fall asleep at night because then my fantasies become real, and I watch every episode and re-run of Top Gear to see him.

I should be going out on dates - but men are never as witty or intelligent as him.

What on earth makes a woman my age irrationally fall for a person on TV? Don't tell me I'm lonely and in need of a social life, because that's not true.

There was a woman who became obsessed with David Walliams to the extent that she had an injunction taken out against her.

Am I so different - though I have not tried to contact James, nor gone through his rubbish bins?

I never felt this way about my ex-husband, and since I am a Christian I wonder if a higher power is trying to tell me something.

What if he is the only man I will feel this way about? I am desperate, pathetic and frightened of my feelings.

Kay

Well, I've always been a Richard Hammond woman myself, especially after I saw him astride a motorbike.

Seriously, though, when I first read your letter I thought it a spoof (although I don't think I've ever had one) but on reflection I think you're real and so is your 'crush' - if an unattainable fantasy can be anything to do with reality.

I've had other letters from women similarly afflicted.

Last September, a girl told me of her passion for a young actor and reading my reply (sensible stuff about not watching his DVDs and imagining him with the nastiest traits) one or two ladies wrote saying it's not that easy to kick the crush habit.

If this wasn't making you so unhappy I'd tell you to enjoy the dreams and hope you run into a man with similar driving skills.

But I wouldn't want to be responsible for your crush developing into something illegal; the David Walliams story wasn't funny.

You don't want this obsession to ruin your life - and it's starting to do so.

You haven't told me when it all began, so you should go back mentally to analyse what was happening at that time. Was there a trigger? Are you worried about getting older?

If you are serious about wanting to find out what's going on, perhaps you should consider that you have a form of Obsessive Compulsive Disorder (which is far more than compulsively washing hands) and seek help.

Visit www.mind.org.uk to find out more about OCD and start by finding a therapist. No one will think you silly.

Cognitive Behavioural Therapy can be useful, so I think you should forget all that 'higher power' stuff, turn off the TV and do some research.

PS: Oh, and if the letter was a spoof, thanks for prompting my pleasant fantasy of riding pillion with the Hamster.

And finally ...

Why I didn't dig this soggy summer

Back in May I wrote lyrically about our determination to turn our garden into a work of art.

We even gave over one bed to vegetables and did slug patrol each night. No longer.

The washout summer allowed the slugs a field day and gradually I lost interest.

The keen dead-header gradually let the sad little blossom-corpses proliferate and the weeds sprout through the gravel. I've given up on my precious patch.

When I survey the leek tops, helplessly wondering how on earth you know when to pull the things up, I realise I don't care.

The slugs got the peppers, the sorrel and those purple cabbages; when I look at the manky-looking beans I find myself wishing they'd dined on those, too.

Because I don't really want to. Next year, I mutter, I'm giving that bed to easy-care shrubs and buying vegetables.

It all boils down to weather. I love sun and heat, and once danced a jig on the edge of the Ganges when the temperature was in the high 40s.

Had we enjoyed an average British summer - which means more than four hammock days in three months - I swear this garden would have held my interest.

My vision of wandering about in a floaty frock carrying a flower-filled trug would have become real.

Or is it - perhaps - horses for courses? Nowadays we expect a lot of ourselves, partly induced by the information overload which shows everybody multitasking, working long hours, and so on.

Why should I expect to turn into a talented gardener overnight? But I did - like so many people, wanting it all.

Then, when the deluge smashed the unpruned roses, I allowed myself to feel a frazzled failure.

Time for a break. Since I began, I've written this column for 64 weeks, missing only two in that time.

So we're off on a tour of New England to explore the coastline and lakes and enjoy our first wedding anniversary in the mountains of Vermont.

The column will be back on September 20, but keep the letters coming because I'll read them all when I get back - refreshed by Boston seafood and, I hope, sun.

Write to Bel Mooney, Daily Mail, 2 Derry Street, London W8 5TT, or e-mail bel.mooney@dailymail.co.uk. A pseudonym will be used if you wish. Bel reads all letters but regrets she cannot enter into personal correspondence.